The goal of this proposal is to develop and evaluate a Patient-Mounted MRI-Compatible Shoulder Arthrography Robot for Needle Guidance in Pediatric Interventional Procedures. The body-mounted robot will enable a novel streamlined workflow for pediatric arthrography that will eliminate the need for fluoroscopy while providing accurate needle guidance in the MRI environment. Arthrography is a commonly performed procedure for evaluation of joint condition, including the shoulder, hip, knee, and ankle, among other sites. While this proposal is focused on pediatrics, the techniques developed are applicable to adult procedures as well. The robotic technology developed here will also be applicable to many other needle-based procedures, including biopsy, drainage, and ablation. This proposal is a first step in our long-term goal of offering MRI-guided radiation free procedures to our pediatric patients. MRI scanning is the standard of care for musculoskeletal imaging and therefore musculoskeletal injuries are well suited to MRI-guided interventions. Our specific aims are to: 1. Design, construct, and evaluate a patient-mounted, MRI-compatible robot for shoulder arthrography. The robot will be strapped on the child in the MRI scanner and will precisely orient a needle guide for contrast injection, based on the images. The physician will place the needle manually through the needle guide and inject the contrast once the needle position is verified. A diagnostic MRI will then be obtained to observe the spread of contrast and evaluate the joint condition. 2. Develop a path planning workstation for image-to-robot registration, selection of the target location, and trajectory verification before manual needle insertion. 3. Integrate the robot with the planning workstation and evaluate the system in the MRI environment using anthropomorphic phantoms. Modify the system as needed and complete final testing on Thiel-embalmed cadavers using the MRI research facility at the University of Dundee (UK). 4. Obtain the required approvals and then complete a first-in-human clinical trial in ten pediatric subjects to evaluate the safety and feasibility of the technique.